软土地基中基坑渗透破坏机理和对策

软土地基中基坑渗流诱发的土体破坏是引起基坑工程事故的一个重要因素。针对基坑工程渗流问题的特殊性,探讨了基坑渗透破坏的机理。结合基坑工程典型工况,阐述了进行渗流控制研究的重要意义,讨论了渗流控制的关键问题,对于深基坑的工程施工具有重要的指导意义。     

渗流井取水方式在大会坪水源地的应用

渗流井是一种结构较为复杂且有别于水平井及其他井孔的取水建筑物,利用河床砂砾石层的净化作用,将河水转化为地下水以获得水资源,该工程在干旱半干旱地区作用尤为显著。通过引入“等效渗透系数”,建立研究区的地下水流三维数值模型,分别模拟计算了平水期和枯水期渗流井的出水量,最终确定大会坪研究区的建议开采量为30600 m3/d。     

潮汐河口水库中水力充填堤坝结构的渗控关键技术研究

随着近些年水力充填堤坝结构在潮汐河口水库中的应用和发展,渗流控制技术也随之不断完善。本文以上海青草沙水库工程中的北堤工程为例,论述了水力充填堤坝应用在潮汐河口水库中,其渗流控制技术研究分析过程,为类似工程的设计和研究提供了经验和参考。     

基坑工程管井回灌优化设计探讨

目前基坑管井回灌设计及优化尚无专门成熟的方法,通过不同基坑回灌类型的分析,提出了基坑管井回灌设计原则及设计流程,并对回灌参数进行了探讨,对回灌可施加的最大压力进行了分析,通过285组基坑水文地质数值模型的计算,对比分析了不同渗透各向异性系数、回灌井结构、回灌井位置和保护建（构）筑物位置下的渗流特征,提出了回灌设计综合指数,从经济、技术及施工难度角度综合评估回灌对保护建（构）筑物以及对坑内降水的双重作用,指导抽灌一体化设计。     

东营凹陷金东—柳桥地区油气化探数据中的地表干扰与排除

东营凹陷南斜坡金东—柳桥地区地表条件复杂,化探信号干扰强烈,造成假异常大面积出现。在对金东—柳桥地区油气化探数据中干扰类型识别的基础上,用Mallat小波分析法,发现分析尺度为3时的连续序列呈现出地表干扰信息,由此进行了地表干扰排除。经过封盖条件校正与异常识别,获得了该区油气化探异常。干扰排除后的异常与断层、圈闭及已发现的油气藏或油气显示相吻合,表明这些异常主要反映的是地下油气藏信息。     

A practical and efficient numerical scheme for the analysis of steady state unconfined seepage flows

The scaled boundary finite‐element method (SBFEM), a novel semi‐analytical technique, is applied to the analysis of the confined and unconfined seepage flow. This method combines the advantages of the finite‐element method and the boundary element method. In this method, only the boundary of the domain is discretized; no fundamental solution is required, and singularity problems can be modeled rigorously. Anisotropic and nonhomogeneous materials satisfying similarity are modeled without additional efforts. In this paper, SBFE equations and solution procedures for the analysis of seepage flow are outlined. The accuracy of the proposed method in modeling singularity problems is demonstrated by analyzing seepage flow under a concrete dam with a cutoff at heel. As only the boundary is discretized, the variable mesh technique is advisable for modeling unconfined seepage analyses. The accuracy, effectiveness, and efficiency of the method are demonstrated by modeling several unconfined seepage flow problems. Copyright © 2011 John Wiley & Sons, Ltd.     

Seepage response along an alluvial valley in a semi‐arid catchment in north‐central California

Over a period of 12 months, soil moisture content and potential was monitored in an annual‐grass‐dominated 20 ha catchment in order to determine flow paths leading to exfiltration at the catchment outlet. Water was found to enter the catchment valley either through flow originating in the slopes or through surface infiltration during rainfall events. Although subsurface flow from the slopes to the catchment outlet occurred throughout the year, surface recharge was restricted to a few events during the wet season. In the deeper saturated profile of the valley, flow was directed upwards along the valley edges and gradually became horizontal towards the central axis of the valley. During the peak of the rainfall season, horizontal flow close to the catchment outlet intercepted the gradually sloping surface, resulting in exfiltration. Plants influenced the hydrology of the catchment by removing moisture from the root zone during spring and early summer, resulting in evapotranspiration losses from the vadose zone. Heterogeneities within the valley soil were evident as variable‐permeability layers that resulted in a seasonally confined water table within the valley. This investigation shows that the vadose zone plays an important role in redistributing surface recharge and emphasizes the importance of accounting for effective moisture in low‐yielding catchments with ephemeral surface runoff. Copyright © 2002 John Wiley & Sons, Ltd.     

Analytical solution to 1D coupled water infiltration and deformation in unsaturated soils

An analytical solution to 1D coupled water infiltration and deformation is derived using a Fourier integral transform. Exponential functional forms are used to represent the hydraulic conductivity–pore‐water pressure relationship and the soil‐water characteristic curve. Fredlund's incremental‐linear constitutive model for unsaturated soils is adopted. The analytical solution considers arbitrary initial pore‐water pressure distributions and flux and pressure boundary conditions. The corresponding analytical solutions to coupled steady‐state problems are also obtained. The analytical solutions demonstrate that the coupling of seepage and deformation plays an important role in water infiltration in unsaturated soils. In the early stages of infiltration, the difference between uncoupled and coupled conditions becomes marked over time, and in late stages, the difference caused by the coupling effects diminishes toward the steady state. The difference between the uncoupled and coupled conditions increases with decreasing desaturation coefficient (α). Pore‐water pressure or deformation changes caused by the coupling effects are mainly controlled by the degree of soil volume change due to a change in soil suction (H). The smaller the absolute value of H, the greater the effect of coupling on the infiltration and deformation. The ratio of rainfall intensity to saturated permeability (q/k_s) also has a strong influence on the coupled seepage and deformation. Copyright © 2008 John Wiley & Sons, Ltd.